Okay, but that doesn't read as valid in the face of DMC3 itself having a prequel plot that literally no one asked for or had in mind when 1 and 2 were the only games (with their respective novels), and now and 4 and 5 exist.
At face value, "Vergil's presumed death at 8 is retconned out as he teams up with a bald wizard to claim his birthright for nebulous reasons, and Dante acts like a total tsundere and goes for the ride even though he says he doesn't care, also some girl is there" isn't actually much of a plot and relies somewhat on people knowing who Dante is already and what his deal is as a Son of Sparda (and what Sparda did 2000 years ago) to cover him going to the tower even though he says he doesn't care and he's a reactive protagonist. That could be covered in a novel or an expository dump in a hypothetical world where DMC3 never existed but 4 did, but someone thought it was worth centering a game around it and here it is. And we still got treated to Lady narrating about stuff she didn't exist to experience. Backstory.
Neither is "Dante shoots the Pope and Nero finds out why, in a predictable hidden conspiracy, protagonist-realizes-the-antagonist-is-the-hero-and-his-own-faction-is-the-villain way, also Kyrie is there" much of a plot on it's own because it relies on, again, people being intrigued by Dante as a Son of Sparda and known savior of humanity (to which all previous games serve as backstory to 4) taking a "Heel Turn" and shooting an elderly man presented as innocent, on top of the intrigue of Nero's origins and why he even exists.
And "DMC3 But Everyone Is Older Now, plus Trish and Southern Bimbo Mechanic Reminiscent of Cindy from FFXV are there" is the least plotty plot of all. It absolutely relies on knowing at least what DMC3 is about to understand the rampant fanservice of Vergil being resurrected when everyone considered his development/arc finished at 3 when he willingly chose to stay in Hell and let Dante escape instead of vindictively trapping him there. And the plot itself is piecemeal and split across a novel, a manga, and whatever else.
And even then people still desire a DMC game about Sparda, essentially wanting a game revolving around 2000-year-old backstory up to and including how Sparda Met Dante's Mother.
The series is already reliant on backstory (whether it's what already exists or the kind the game will introduce or reinterpret) to rope people into a thin plot to excuse why they run around slaying demons and engaging in "stylish action". To each successive game, all prior games are History or Backstory especially from the point of view of someone who's introduced to the entire series via any game that's not 1.
So again, what's the difference?